In order to effectively counteract defects of the kind described above, numerous electronic engine controls have diagnostic methods for checking the drive output stage of the injection valve. If the diagnosis provides the result that an injection valve no longer can be closed, then the fuel pump is switched off in arrangements known in the state of the art. This has the serious disadvantage that the affected vehicle becomes disabled. A further disadvantage is that the residual fuel in the lines can continue to be injected and this residual amount can be sufficient for destroying the catalyzer.